The invention relates to a radio unit for a radio telephone set wherein said radio unit is interconnected with at least one disconnectable phone module.
Cellular or mobile phones are, for various uses, comprised of different combinations of a radio unit and a phone module. A mobile phone, a portable phone, a hand-portable phone and a mobile phone with a separate battery, for example, are involved. A mobile phone with a separate battery is called a bag phone. In certain types of telephones a number of similar batteries with similar voltage limits can be used. The prior art radio telephone can also identify the difference in whether the phone element uses its own battery or if the phone is fed by an external power supply.
Patent application EP 90304320.6. published on Oct. 24, 1990 with the number 394074 discloses a method and apparatus for determining the battery type and for modifying operating characteristics accordingly.
The diversity of different combinations, as well as the costs entailed with short production runs and a larger number of production lines, respectively, are drawbacks in the present cellular phone production.